In certain applications involving chemical and/or physical reactions, presence of light having any of a specified set of wavelengths will cause the reaction to proceed, whereas absence of all of this specified set of wavelengths will either suppress the reaction or will cause the reaction to proceed at a markedly lower rate or to fail to go to completion. In some situations, it is desirable to determine which of two or more groups of wavelengths within the specified set was present, if the reaction proceeds, to correlate the wavelengths present with an observed reaction rate or for some other purpose. In other situations, it is desirable to provide separate groups of non-overlapping wavelengths and to monitor the reaction simultaneously or sequentially for reaction rate and/or completion of the reaction.
What is needed is a system that provides N-dimensional control (with N=2 or 3) of direction of propagation of a light beam, that varies this direction according to a representative wavelength of the light beam, and that provides simultaneous separation of the light beam into different wavelength groups that are directed to different detectors or reaction sites. Preferably, the system should provide a light beam propagation direction that varies monotonically with wavelength in a selected wavelength interval.